Hadronic vacuum polarization of the muon on 2+1+1-flavor HISQ ensembles: an update

TL;DR

This paper updates the lattice QCD calculation of the light-quark hadronic vacuum polarization contribution to the muon's anomalous magnetic moment using advanced ensembles and noise reduction techniques.

Contribution

It provides preliminary, blinded results for the intermediate window contribution on 2+1+1 flavor HISQ ensembles with physical pion mass and introduces improved noise reduction methods for two-pion contributions.

Findings

Preliminary results for $a_{\mu, \textrm{W}}^{ll}$ on multiple lattice spacings.

Fourfold noise reduction in two-pion correlation function study.

Consistent results across different lattice spacings.

Abstract

We give an update on the status of the Fermilab Lattice-HPQCD-MILC calculation of the contribution to the muon's anomolous magnetic moment from the light-quark, connected hadronic vacuum polarization. We present preliminary, blinded results in the intermediate window for this contribution, $a_{\mu, \textrm{W}}^{ll}$. The calculation is performed on $N_f =2+1+1$ highly-improved staggered quark (HISQ) ensembles from the MILC collaboration with physical pion mass at four lattice spacings between 0.15 fm and 0.06 fm. We also present preliminary results for a study of the two-pion contributions to the vector-current correlation function performed on the 0.15 fm ensemble where we see a factor of four improvement over traditional noise reduction techniques.